Search Results (2,982)

Biofilms are a spontaneously formed slimy matrix of extracellular polymeric substances (EPS) enveloping miniature bacterial colonies, which aid in pathogen colonization, shielding the bacteria from antibiotics, as well as imparting them resistance towards the same. Biofilms employ a robust communication mechanism called quorum sensing that serves to keep their population density constant. What is most significant about biofilms is that they contribute to the development of bacterial virulence by providing protection to pathogenic species, allowing them to colonize the host, and also inhibiting the activities of antimicrobials on them. They grow on animate surfaces (such as on teeth and intestinal mucosa, etc.) and inanimate objects (like catheters, contact lenses, pacemakers, endotracheal devices, intrauterine devices, and stents, etc.) alike. It has been reported that as much as 80% of human infections involve biofilms. Serious implications of biofilms include the necessity of greater concentrations of antibiotics to treat common human infections, even contributing to antimicrobial resistance (AMR), since bacteria embedded within biofilms are protected from the action of potential antibiotics. This review explores various contemporary strategies for controlling biofilms, focusing on their modes of action, mechanisms of drug resistance, and innovative approaches to find a solution in this regard. This review interestingly targets the extracellular polymeric matrix as a highly effective strategy to counteract the potential harm of biofilms since it plays a critical role in biofilm formation and significantly contributes to antimicrobial resistance. Full article

This study investigates the effectiveness of contact and online biology teaching by assessing student performance and gathering perceptions from students, teachers, and parents. Conducted in autumn 2021 with 3035 students, 124 biology teachers, and 719 parents, this study combined post-instruction assessments of student performance in knowledge reproduction and conceptual understanding with questionnaires examining perceptions of contact and online biology teaching effectiveness across students, teachers, and parents. To investigate how various teaching-related factors influence perceived understanding of biological content, we applied a CHAID-based decision tree model to questionnaire responses from students, teachers, and parents. Results indicated that students value engaging, flexible instruction, sufficient time to complete tasks and support for independent thinking. Teachers emphasized their satisfaction with teaching and efforts to support student understanding. In contact lessons, students preferred problem-solving, teacher guidance, and a stimulating environment. In online learning, they preferred low-stress, interesting lessons with room for independent work. Parents emphasized satisfaction with their child’s learning and the importance of a focused, stimulating environment. This comparative analysis highlights the need for student-centered, research-based biology teaching in both formats, supported by teachers and delivered in a motivating environment. The results offer practical insights for improving biology instruction in different teaching modalities. Full article

During the process of oil and gas drilling, due to the existence of pores or micro-cracks, drilling fluid is prone to invade the formation. Under the action of hydration expansion of clay in the formation and liquid pressure, wellbore instability occurs. In order to reduce the wellbore instability caused by drilling fluid intrusion into the formation, this study proposed a method of forming a dynamic hydrogen bond cross-linked network weak gel structure with modified nano-silica and P(AM-AAC). The plugging performance of the drilling fluid and the performance of inhibiting the hydration of shale were evaluated through various experimental methods. The results show that the gel composite system (GCS) effectively optimizes the plugging performance of drilling fluid. The 1% GCS can reduce the linear expansion rate of cuttings to 14.8% and increase the recovery rate of cuttings to 96.7%, and its hydration inhibition effect is better than that of KCl and polyamines. The dynamic cross-linked network structure can significantly increase the viscosity of drilling fluid. Meanwhile, by taking advantage of the liquid-phase viscosity effect and the physical blocking effect, the loss of drilling fluid can be significantly reduced. Mechanism studies conducted using zeta potential measurement, SEM analysis, contact angle measurement and capillary force assessment have shown that modified nano-silica stabilizes the wellbore by physically blocking the nano-pores of shale and changing the wettability of the shale surface from hydrophilic to hydrophobic when the contact angle exceeds 60°, thereby reducing capillary force and surface free energy. Meanwhile, the dynamic cross-linked network can reduce the seepage of free water into the formation, thereby significantly lowering the fluid loss of the drilling fluid. This research provides new insights into improving the stability of the wellbore in drilling fluids. Full article

Steel is an important product in many engineering sectors; however, steelmaking remains one of the largest ${\mathrm{CO}}_2$ emitters. Therefore, new governmental policies drive the steelmaking industry toward a cleaner and more sustainable operation such as the gas-based direct reduction–electric arc furnace process. To become carbon neutral, utilizing more scrap is one of the feasible solutions to achieve this goal. Addressing knowledge gaps regarding scrap heterogeneity (size, shape, and composition) is essential to evaluate the effects of increased scrap ratios in basic oxygen furnace (BOF) operations. This review systematically examines heat and mass transfer correlations relevant to scrap melting in BOF steelmaking, with a focus on low Prandtl number fluids (thick thermal boundary layer) and dense particulate systems. Notably, a majority of these correlations are designed for fluids with high Prandtl numbers. Even for the ones tailored for low Prandtl, they lack the introduction of the porosity effect which alters the melting behavior in such high temperature systems. The review is divided into two parts. First, it surveys heat transfer correlations for single elements (rods, spheres, and prisms) under natural and forced convection, emphasizing their role in predicting melting rates and estimating maximum shell size. Second, it introduces three numerical modeling approaches, highlighting that the computational fluid dynamics–discrete element method (CFD–DEM) offers flexibility in modeling diverse scrap geometries and contact interactions while being computationally less demanding than particle-resolved direct numerical simulation (PR-DNS). Nevertheless, the review identifies a critical gap: no current CFD–DEM framework simultaneously captures shell formation (particle growth) and non-isotropic scrap melting (particle shrinkage), underscoring the need for improved multiphase models to enhance BOF operation. Full article

Enhancer-promoter interactions occur in the chromatin loci delineated by the CCCTC-binding zinc-finger protein CTCF. CTCF binding is frequently perturbed in genetic disorders and cancer, allowing for misregulation of genes. Here, we developed a panel of chimeric proteins consisting of either full-length or truncated CTCF fused with programmable DNA-binding module dCas9 and fluorescent tracker EGFP. We found that the recruitment of a chimeric protein based on the CTCF N-terminal domain and two zinc-finger domains to the human HOXD locus leads to the de novo formation of a spatial contact with a nearby cohesin/CTCF-bound region, anchoring several chromatin loops. This chimeric protein did not show binding to CTCF motifs and did not affect the epigenetic and transcription profile of the locus. Recruitment of this chimeric protein is also able to restore chromatin loops, lost after deletion of an endogenous CTCF-binding site. Together, our data indicate that the ectopic recruitment of the CTCF N-terminal part could be an appropriate tool for 3D genome engineering. Full article

The thermo-chemical treatment of dental implants leads to the formation of sodium titanate crystals on their surface. When in contact with blood, these crystals dissolve and trigger an ionic exchange cascade, resulting in the formation of a calcium apatite layer. This study, carried out both in vitro and in an animal model, aimed to determine whether the cooling rate of the treatment affects the size of the deposited crystals, and whether this in turn influences wettability and early bone-to-implant contact (BIC). A total of 50 dental implants and 50 titanium discs were treated using four different cooling rates, along with a control group. Crystal size was analyzed on implant surfaces using scanning electron microscopy, and wettability was assessed on titanium discs using a goniometer. Finally, the implants were placed in the tibiae of 13 rabbits, and histological analysis was performed after three weeks to compare BIC among groups. Results suggest that a cooling rate of 75 °C/h produces smaller sodium titanate crystals, which are associated with significantly improved surface wettability and a higher percentage of bone-to-implant contact after 3 weeks of healing (p < 0.05). Full article

Protein–polyelectrolyte nanostructures assembled via electrostatic interactions offer versatile applications in biomedicine, tissue engineering, and food science. However, several open questions remain regarding their intermolecular interactions and the influence of external conditions—such as temperature and pH—on their assembly, stability, and responsiveness. This study explores the formation and stability of networks between poly(acrylic acid) (PAA) and lysozyme (LYZ) at the nanoscale upon thermal treatment, using a combination of experimental and simulation measures. Experimental techniques of static and dynamic light scattering (SLS and DLS), Fourier transform infrared spectroscopy (FTIR), and circular dichroism (CD) are combined with all-atom molecular dynamics simulations. Model systems consisting of multiple PAA and LYZ molecules explore collective assembly and complexation in aqueous solution. Experimental results indicate that electrostatic complexation occurs between PAA and LYZ at pH values below LYZ’s isoelectric point. This leads to the formation of nanoparticles (NPs) with radii ranging from 100 to 200 nm, most pronounced at a PAA/LYZ mass ratio of 0.1. These complexes disassemble at pH 12, where both LYZ and PAA are negatively charged. However, when complexes are thermally treated (TT), they remain stable, which is consistent with earlier findings. Atomistic simulations demonstrate that thermal treatment induces partially reversible structural changes, revealing key microscopic features involved in the stabilization of the formed network. Although electrostatic interactions dominate under all pH and temperature conditions, thermally induced conformational changes reorganize the binding pattern, resulting in an increased number of contacts between LYZ and PAA upon thermal treatment. The altered hydration associated with conformational rearrangements emerges as a key contributor to the stability of the thermally treated complexes, particularly under conditions of strong electrostatic repulsion at pH 12. Moreover, enhanced polymer chain associations within the network are observed, which play a crucial role in complex stabilization. These insights contribute to the rational design of protein–polyelectrolyte materials, revealing the origins of association under thermally induced structural rearrangements. Full article

Whether the spongiotic reaction caused by the interaction of keratinocytes, T-lymphocytes, inflammatory dendritic epidermal cells (IDECs), and Langerhans cells (LCs) observed in atopic dermatitis (AD) represents a common feature of spongiosis in various skin diseases remains unclear. We analyzed the characteristics of spongiosis in AD compared with those in other eczematous dermatitis and inflammatory skin diseases by using immunohistochemical methods. Infiltration of IDECs (CD11c+ cells and/or CD206+ cells) and T-lymphocytes, accompanied by degenerated keratinocytes and aggregated LCs (CD207+ cells), was frequently observed as a common feature of spongiosis in multiple conditions. However, IDECs expressing IgE were identified exclusively in IgE-mediated AD. Aggregation of IDECs was predominantly observed in the spongiosis of adaptive immune-mediated eczematous disorders, such as AD and allergic contact dermatitis. These IDEC aggregations constituted the major components of the epidermal dendritic cell clusters seen in AD and other eczematous or eczematoid dermatoses, and may serve as a useful distinguishing marker from Pautrier collections seen in cutaneous T-cell lymphoma. These findings suggest that IDECs, in cooperation with other immune cells, may play a pivotal role in spongiosis formation in AD and various skin diseases, although the underlying immunopathological mechanisms differ among these conditions. Full article

Quinoa protein isolate (QPI) and sodium alginate (SA) have excellent biocompatibility and functional properties, making them promising candidates for food-grade delivery systems. In this study, we developed, for the first time, a QPI/SA complex-stabilized Pickering emulsion for curcumin encapsulation. The coacervation behavior of QPI and SA was investigated from pH 1.6 to 7.5, and the structural and interfacial characteristics of the complexes were analyzed using zeta potential measurements, Fourier-transform infrared spectroscopy, scanning electron microscopy, and contact angle analysis. The results showed that the formation of QPI/SA complexes was primarily driven by electrostatic interactions, hydrogen bonding, and hydrophobic interactions, with enhanced amphiphilicity observed under optimal conditions (QPI/SA = 5:1, pH 5). The QPI/SA-stabilized Pickering emulsions demonstrated excellent emulsification performance and storage stability, maintaining an emulsification index above 90% after 7 d when prepared with 60% oil phase. In vitro digestion studies revealed stage-specific curcumin release, with sustained release in simulated gastric fluid (21.13%) and enhanced release in intestinal fluid (88.21%). Cytotoxicity assays using HeLa cells confirmed the biocompatibility of QPI/SA complexes (≤500 μg/mL), while curcumin-loaded emulsions exhibited dose-dependent anticancer activity. These findings suggest that QPI/SA holds significant potential for applications in functional foods and oral delivery systems. Full article

Background: The role of collagen membrane fixation during guided bone regeneration (GBR) remains debatable, particularly in post-extraction sockets with buccal defects and concomitant immediate implant placement. This study evaluated whether or not fixation with titanium pins improved regenerative outcomes. Methods: Six adult Beagle dogs received bilateral extractions of the fourth mandibular premolars. An implant was immediately placed in both the distal alveoli, and standardized buccal bone defects (5 mm height, 3–2 mm width) were prepared. All defects were filled with a slowly resorbing equine xenograft and covered by a resorbable pericardium membrane. At the test sites, the membrane was apically fixed with pins, while no fixation was applied to the control sites. After 3 months of healing, histomorphometric analyses were performed. Results: The vertical bone gain of the buccal crest was 3.2 mm in the test sites (pin group) and 2.9 mm in the control sites (no-pin) (p > 0.754). No significant difference was found in terms of bone-to-implant contact (BIC). However, residual graft particles were located significantly more coronally in the pin group compared to the no-pin group (p = 0.021). Morphometric analyses revealed similar new bone formation within the groups, but with higher amounts of residual xenograft and soft tissue in the pin group. Conclusions: Membrane fixation did not significantly enhance vertical bone gain, and although the slightly higher regeneration in the pin group (3.2 mm vs. 2.9 mm) may hold clinical relevance in esthetically sensitive areas and osseointegration, it appeared to limit apical migration of the grafting material. Full article

Enhancing osseointegration is a common goal for many titanium implant coatings, since the naturally forming oxides are often bioinert and exhibit less than ideal bone-to-implant contact. Oxide coating surface topographies, chemistries, and crystallinities are known to play key roles in enhancing bone–implant interactions. In the present study, two novel anodization processes were developed in electrolytes based on juiced navel oranges to create bioactive oxide coatings on commercially pure titanium (CPTi) surfaces. Both oxide groups revealed multi-scaled micro and nano surface topographies, significant Ca and P-dopant incorporation exhibiting Ca/P ratios similar to human bone (1.7 and 1.8), and physiologically relevant Mg uptake levels of <0.1% and 1.4 at%. XRD and FTIR analyses of each oxide revealed a combination of tricalcium phosphate and hydroxyapatite phases that showed carbonate substitutions indicative of bone-like apatite formation. Finally, VDI indentation testing revealed good adhesion strengths, minimal cracking, and no visible delamination for both oxides. In summary, the anodization processes in the present study were shown to produce carbonated tricalcium phosphate and apatite containing oxides with contrasting levels of Mg uptake that show much promise to improve future implant clinical outcomes. Full article

Water systems are highly vulnerable to biofilm formation, which can compromise water quality, operational efficiency, and public health. Factors such as surface material properties and gravitational orientation of the surface play critical roles in the early stages of microbial attachment and biofilm development. This study examines the impact of gravity and surface composition on the initial adhesion of Pseudomonas fluorescens AR11—a model organism for biofilm research. Focusing on stainless steel (SS) and polycarbonate (PC), two materials commonly used in water and wastewater infrastructure, bacterial adhesion was evaluated at surface inclinations of 0°, 45°, 90°, and 180° to assess gravitational impact. After three hours of contact, fluorescence microscopy and image analysis were used to quantify surface coverage and cluster size distribution. The results showed that both material type and orientation significantly affected early biofilm formation. PC surfaces consistently exhibited higher bacterial adhesion at all angles, with modest variations, suggesting that material properties are a dominant factor in initial colonization. In contrast, SS showed angle-dependent variation, indicating a combined effect of gravitational convection and surface characteristics. These insights contribute to a deeper understanding of biofilm dynamics under realistic environmental conditions, including those encountered in space systems, and support the development of targeted strategies for biofilm control in water systems and spaceflight-related infrastructure. Full article

The transition to sustainable energy systems demands efficient recycling methods for critical raw materials like lithium. In this study, we present a new class of pH- and light-switchable flotation collectors based on isomeric derivatives of the natural product Punicine, termed inverse Punicines. These amphoteric molecules were synthesized via a straightforward four-step route and structurally tuned for hydrophobization by alkylation. Their performance as collectors was evaluated in microflotation experiments of lithium aluminate (LiAlO₂) and silicate matrix minerals such as melilite and calcium silicate. Characterization techniques including ultraviolet-visible (UV-Vis), nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectroscopy as well as contact angle, zeta potential (ζ potential) and microflotation experiments revealed strong pH- and structure-dependent interactions with mineral surfaces. Notably, N-alkylated inverse Punicine derivatives showed high flotation yields for LiAlO₂ at pH of 11, with a derivative possessing a dodecyl group attached to the nitrogen as collector achieving up to 86% recovery (collector conc. 0.06 mmol/L). Preliminary separation tests showed Li upgrading from 5.27% to 6.95%. Radical formation and light-response behavior were confirmed by ESR and flotation tests under different illumination conditions. These results demonstrate the potential of inverse Punicines as tunable, sustainable flotation reagents for advanced lithium recycling from complex slag systems. Full article

Background and Objectives: Posterior chamber phakic implantable contact lenses (Phakic-ICL) are widely used for refractive correction due to their efficacy and safety, including minimal corneal endothelial cell loss. The Collamer-based EVO+ Visian implantable contact lens (ICL), manufactured from Collamer, which is a blend of collagen and hydroxyethyl methacrylate (HEMA), has demonstrated excellent long-term biocompatibility and optical clarity. Recently, hydrophilic acrylic Phakic-ICLs, such as the Implantable Phakic Contact Lens (IPCL), have been introduced. This study investigated the material differences among Phakic-ICLs and their interaction with fibronectin (FN), which has been reported to adhere to intraocular lens (IOL) surfaces following implantation. The aim was to compare Collamer, IPCL, and LENTIS lenses (used as control) in terms of FN distribution and cell adhesion using a small number of explanted Phakic-ICLs. Materials and Methods: Three lens types were analyzed: a Collamer Phakic-ICL (EVO+ Visian ICL), a hydrophilic acrylic IPCL, and a hydrophilic acrylic phakic-IOL (LENTIS). FN distribution and cell adhesion were evaluated across different regions of each lens. An in vitro FN-coating experiment was conducted to assess its effect on cell adhesion. Results: All lenses demonstrated minimal FN deposition and cellular adhesion in the central optical zone. A thin FN film was observed on the haptics of Collamer lenses, while FN adhesion was weaker or absent on IPCL and LENTIS surfaces. Following FN coating, Collamer lenses supported more uniform FN film formation; however, this did not significantly enhance cell adhesion. Conclusions: Collamer, which contains collagen, promotes FN film formation. Although FN film formation was enhanced, the low cell-adhesive properties of HEMA resulted in minimal cell adhesion even with FN presence. This characteristic may contribute to the long-term transparency and biocompatibility observed clinically. In contrast, hydrophilic acrylic materials used in IPCL and LENTIS demonstrated limited FN interaction. These material differences may influence extracellular matrix protein deposition and biocompatibility in clinical settings, warranting further investigation. Full article

In order to improve the lubrication efficiency in the bearing cavity, this study establishes a simulation model of the fluid domain of the bearing cavity based on the computational fluid dynamics (CFD) method and systematically studies the flow characteristics of the lubricant and its lubrication mechanism in the high-speed rotary bearing. In the process of high-speed bearing operation, the lubricant is subject to the combined effect of centrifugal force and contact pressure, gradually spreads to both sides of the steel ball, and forms a stable oil film after injection from the nozzle. However, due to the influence of high pressure distribution in the contact area, the actual formation of the oil film coverage is relatively limited. In order to further optimize the lubrication effect, this study focuses on investigating the influence law of different injection speeds and rotational speeds on the bearing air curtain effect. The results of the study show that when the air curtain effect is enhanced, there will be significant shear interference on the trajectory of the lubricant, which is manifested in the phenomenon of “buckling” at the end of the lubricant, thus reducing the lubrication efficiency. To address this problem, this study innovatively proposes the air curtain obstruction coefficient K as a quantitative evaluation index, and through numerical simulation, it is found that the lubricant can effectively overcome the air curtain obstruction and achieve a better lubrication coverage when the value of K is reduced to below 0.4. Based on this finding, the study further confirmed that the lubrication efficiency of bearings can be significantly improved under different operating conditions by rationally regulating the injection rate. Full article